Furnace grate



June l, -R W, FOSTER 2,082,201

FURNACE GRATE Filed Jan. 24, 1956 4 sheets-sheet 1 .5g .53 E@ E .30

June 1, 1937. R.w. FOSTER 2,082,201

FURNACE ,GRATE Filed Jan. 24, 195e 4 sheetswsheet 2 R. W. FOSTER FURNACE GRATE June l, 1937.

Filed Jan. 24, 1936 4 Sheets--SheefI 5 -7, MMM

@u 76 6 A2 W w 4 Il June l, 1937. R w, FOSTER 2,082,201

FUHNACE GRATE Filed Jan. 24, 1936 4 sheets-sheet 4 aten Patented June 1, 1937 UNITED STATES PATET OFFICE FURNACE GRATE Application January 24, 1936, Serial No. 60,593

9 Claims.

This invention relates to furnace grates.

One of the principal objects of the invention is to provide an improved furnace grate construction.

A further object of the invention is to provide an improved furnace grate providing for eX- pansion of the grate elements without material eect on the passage of air through the grate.

A further object of the invention is to provide an improved furnace grate having independent movable grate elements which will not become cemented together by clinkers to an objectionable degree.

A further object of the invention is to provide an improved grate assembly in which the parts which may be burned out may be readily removed and replaced. y

Other objects, advantages and capabilities of the invention will appear from the following description of a preferred embodiment thereof taken in conjunction with the accompanying drawings, in which- Fig. 1 is a longitudinal sectional elevation of a furnace embodying my invention;

Fig. 2 isa fragmentary sectional View taken on the line 2 2 of Fig. l, showing the forward part of the grate in plan;

Fig. 3 is a vertical sectional View taken on the line 3 3 of Fig. 2; v

Fig. 4 is a fragmentary elevational view showing one of the side hangers and the manner in which associated parts are mounted thereon;

Fig. 5 is a sectional view therethrough, taken on the line 5-5 of Fig. 4;

Fig. 6 is a sectional view therethrough, taken on the line Iig-6 of Fig. 4;

Fig. 7 is a view similar to Fig. 6, showing the central hanger;

Fig. 8 is a sectional detail view, taken on the line 8-8 of Fig. 2; l

Fig. 9 is a sectional detail View, taken on the line 9-9 of Fig. 2; and

Fig. 10 is a perspective View of a portion of the end lock bar.

Referring to the accompanying drawings, the reference numeral II designates a ledge formed on the masonry adjacent the arch. On the ledge II is loosely laid a channel I2 resting on one of its sides. At the front of the furnace a dead plate I3 is built into the masonry side walls of the furnace. At its center the dead plate I3 is supported by a bracket I4 carried by the front plate I5 of the furnace.

The dead plate I3 comprises a rearwardly projecting ledge I6 which serves as a forward support for the grate han-gers I 1. These hangers are of suitable number depending upon the width of the furnace. Thus, in the furnace illustrated, three hangers Il are employed, one at each side, and one in the middle of the furnace. The 5 rear ends of the hangers rest upon the lower web of the channel I2.

The cross section of one of the side hangers can be seen in Fig. 5. The hanger comprises an upper rail portion which is reinforced longitu- 10 dinally by a lower depending rib I8 of downwardly convex formation, as' viewed in Figs. 1,

4 and 8. The upper rail portion has an outer at vertical face I9. The inner face is provided with a relatively large longitudinal groove 20 15 of rectangular form. Above the groove the thickness of the rail portion is preferably reduced somewhat. The upper surface 2| slopes downwardly and inwardly sharply to provide an effective inclined plane. 20

The hanger I'I is provided along its length with notches 21 which extend downwardly from its upper edge. These notches are intended to receive the trunnions 22 of the grate bars and are spaced equidistantly and provide bearings at a 25 single level. The ends of the hangers I1 are enlarged laterally, as shown at 23, to provide stable support for the hangers. When mounted in the furnace the side hangers I1 are located close to the side walls of the furnace chamber. 30

The central hanger I l, or the intermediate hangers, if more than three hangers are employed, are of similar construction to the side hangers just described, but they are symmetrical having sloping surfaces 2I on each side and hav- 35 ing grooves 2D on opposite sides. The central or intermediate hangers are also thicker than the side hangers since they have to carry twice the load. It is to be noted that each of their notches 2'! receive two trunnions 22 of the grate bars on 40 opposite sides.

The grate bars comprise grate plates 24 and trunnion bars 25. Each trunnion bar 25 carries a trunnion 22 at each end whereby the grate bar is pivotally mounted in the notches 21 of the 45 adjacent hangers Il. Between its ends the trunnion bar 25 comprises two spaced longitudinal strips 2B which are connected together at suitable points along their length' by bridge pieces 12. jacent their lower edges by bridge pieces 28 which are provided with openings through which pass the bolts 29 which secure the grate plate 24 to the trunnion bar 25.

Each grate plate 24 is preferably of rectangular 55 The strips 26 are also connected ad- 50 form, as Shown in Fig. 2, and is provided with relatively narrow perforations 30, whereby the air can pass upwardly into the fuel bed. These perforations are preferably arranged in herringbone pattern, although they may be otherwise arranged if desired. Adjacent each end the grate plate is provided with a boss 3| which is recessed to receive the head 32 of the bolt 29. The boss 3| is provided with depending projections 33 which extend into the space between the strips 26 of the bar 25.

It will readily be understood with reference to Fig. 9 that the nuts 34 firmly unite the grate plate 24 to the trunnion bar 25 and that theprojections 33 hold the plate 24 against displacement in theV vided at their upper edges with outwardly directed flanges 13. 'Ihe bosses 3| are provided with projections 35 which engage the outer corners of these flanges.

, Each -grate plate 24 is provided around its edge, with the exception of the portions occupied by the trunnion bar 25, with a depen-dent skirt 36. This skirt is provided with numerous perforations 31 so that it remains cold at all times. The skirt 36 is preferably substantially triangular in section, and its outer face is displaced inwardly to some extent so that it does not foul the grate plate of the adjacent gratebar when the grate bars are moved to the tilted position shown in Fig. 8.

Each trunnion bar 25 has integrally formed therewith a depending arm 38. The arms 38 of series of Vgrate bars are connected to a single gang bar 39, which Ycan be moved backwards and forwards t0 the desired extent by means of a lever 4D mounted on the front plate of the furnace, which lever is connected by means of a link 4| and adjustable connecting element 42 -to the gang bar 39. Y

It will be understood that in normal condition the grate bars are located horizontally so that they present a perforated fiat surface for the reception and support of the fuel during combustion. This kcondition is shown in Fig. 1, and it will benoted that the depending arms 38 are substantially sloped from the vertical. In this particular instance, the arms 38 are sloped forwardly.

The arrangement of the grates is such that the lever 40 maybe moved away from the furnace to a slight `extent so as to tilt the YgrateY bars towards the rear to a slight extent, which may be useful in breaking up clinkers. lhen, however, the lever 4U is moved rearwardly, the gang bar 39 is moved in .the same direction, with the result that the grate bars tilt forwardly as shown in Fig. 8. When this rearward movement of the Vgang bar 39 is `continued sufficiently, the grate plates 24 may attain a vertical position, this being rendered possible by the obliquity'of the arms 38, previously referred to.

At each end vof the grate bars I provide-a grate expansion lock bar43, which is best seen in Fig. 6. The lock bar has an upper portion 44 which has a slope corresponding to the slope Vof the surfaces 2| of the hangers I1. On its -inner side and below the upper sloping portion the lock bar 43 is provided with a ledge 45, which normally projects freely into the associated groove 2l); that is, it extends into this groove with clearance in all directions, for a purpose which will hereinafter be more fully described.

It is Ato be noted, however, that this lock bar is held in assembled relation to the furnace grate by this ledge, and that the bar cannot be removed until the grate bars are disassembled.

The vertical depending portion 46 is adapted to extend along the ends of the grate plates 24, as shown in Figs. 8 and 9. 'I'hese ends normally make contact with the lock bars. The exterior faces of the lock bars 43 are fluted so as to provide passages for air over their surface and between the ends of the grates 24 and the lock bars.

It will readily be understood that when the gratesy 24- expand, the lock bars 43 will be moved laterally. In so doing the upper sloping portions 44 will slide upwardly upon the surfaces 2|. It is to be understood, of course, that the clearance provided is ample to take care of any expansion which may be experienced. When the grate bars 24 contract, the bars 43 are free to move inwardly and theyare caused t0 move inwardly by the sloping surfaces 2.| upon which they rest.

, It will readily be understood that the movable arrangement of these Ylock bars has the effect of maintaining a constant relation between thek grate bars and the members at their ends. Owing to this constant relation, the air flow is maintained uniform. Changes of temperature of the grate bars have no effect upon the iiow of air around the ends of the grate bars, as has heretofore been the case.

The grate lock bars 43 are provided at regular intervals with depending pieces 41 whichV are adapted to enter into the notches 21. These pieces 41 have their lower surface of arcuate form, corresponding to the trunnions 22. Itis to be noted, however, that these pieces 41 are normally in spaced relation to the trunnion 22 so as to provide for the free movement of the lock bars 43 when the grates contract.

The hangers |1 are rigidly secured together by means of the tie bars 48 located at .their forward and rearward ends. These tie bars are secured` to the hangers |1 by means `of angles 48 and bolts 50. The channel |2 is cut away, .as shown at. 5|, for the accommodation of the angles 49.

It will be understood that the dead plate I3 is located within the furnace so as to provide the proper space for the mounting of the hangers I1. Any small amount of variation is provided by locating the Vdead plate I3 rearwardly with vrespect to the front plate of the furnace. The dead plate |3 has an opening 52, which is normally bridged over by tuyres 53. These tuyres are perforated and form a rigid hearth. The space between the forward ends of the tuyres and the front plate l5 of the furnace may be filled with masonry 54. Y

The present embodiment of the invention is described in connection with a furnace which may be provided with an automatic-Stoker 55 of the type described-and claimed in my rco-pending application, Serial No. 60,592, filed January 24, 1936 (Case 1). The improved furnace grate, however, can be employed with other furnaces. The furnace illustrated is intended to be used in connection with forced draft, the air being supplied at the rear of the furnace through aduct 5B. The air passes upwardly through the 4openings in the tuyres 53 through openings in the tie bars 48 and through the openings in the grate plates 24. The air also passes around the trunnions 22 and upwardly behind lock bars 43, so that they are effectively cooled.

'Ihe air makes its Vway upwardly between the grate plates 24 and the lock plates 43, the latter upward passage of the air being facilitated by the fluting on the lock bars 43. The open structure of the trunnion bars 25 permits the air to ow upwardly between the strips 26 and through the openings in the grate plates 261. Consequently, the grate structure as a whole is effectively cooled. The only portions which are directly exposed to the heat are the plates 2G and the lock bars 43, and the passage `of the air over and through these elements maintains their temperature at a remarkably low degree. The skirts 35 of the grate plates 24 are exposed to. the incoming cold air. The openings 3l in these skirts aid in maintaining them at a very low temperature. As a result of this low temperature any clinker which may tend to flow downwardly between the adjacent edges of the grate plates 24 is immediately chilled very near the upper surface of these plates. Consequently, the amount of clinker which may form between the grate plates Ztis strictly limited, and it may be broken easily by a suitable movement of the grate bars.

It may here be remarked that the grate bars are movable from their normal position in both directions. In one direction, the possible movement is slight, but is sufcient to aid materially in breaking up any clinker formed between the grate bars. The movement in the other direction enables the grate plates 24 to be moved into substantially Vertical or complete dumping position.

Although the invention has been-described in connection with the specific details of a preferred embodiment thereof, it must be understood that such details are not intended to be limitative oi the invention, except in so far as set forth in the accompanying claims. Having thus described my invention, I declare that what I claim is:

1. A furnace grate structure comprising a grate member, means for supporting the grate member, an end bar, and means supporting said end bar whereby it is caused by gravity to move into contact with said grate member.

2. A furnace grate structure comprising a grate member, means for supporting the grate member, an end bar adapted for a certain degree of free movement towards and away from said grate member, and supporting means for said end bar having an inclined surface in Contact with said bar whereby gravity tends to move said bar into contact with the grate member.

3. A furnace grate structure comprising a grate member, means for supporting the grate member, an end bar adapted for a certain degree of free movement towards and away from said grate member, and supporting means for said end bar, said bar having an inclined surface in Contact with said supporting means whereby gravity tends to move said bar into contact with the grate member.

4. A furnace grate structure comprising a plurality of hangers, grate members pivotally mounted on said hangers, said hangers having at their upper ends, inwardly and downwardly inclined surfaces, and end bars engaging said surfaces and said grate members and capable of moving on said hangers in accordance with the contraction and expansion of the grate member.

5. A furnace grate structure comprising a plurality of hangers, grate members pivotally mountled on said hangers, and end bars engaging the grate members and having inclined surfaces which engage the hangers to support the end bars thereon in such manner that the end bars are capable of moving on said hangers in accordance with the contraction and expansion of the grate members while remaining in contact with said members.

6. A furnace grate structure comprising a plurality of hangers, grate plates extending between said hangers, trunnion bars pivotally mounted in said hangers and carrying said plates, said hangers having upper surfaces which slope downwardly and inwardly, and lock bars having sloping upper portions supported on the sloping hanger surfaces and lower portions extending between the grate plates and the hangers.

7. A furnace grate structure comprising a plurality of hangers, grate plates extending between said hangers, trunnion bars pivotally mounted in said hangers and carrying said plates, said hangers having upper surfaces which slope downwardly and inwardly, lock bars having sloping upper portions'supported on the sloping hanger surfaces and lower portions extending between the grate plates and the hangers, and means on said hangers and lock bars preventing the upward removal of said lock bars.

8. A furnace grate structure comprising a plurality of hangers, grate'plates extending between said hangers, trunnion bars pivotally mounted in said hangers and carrying said plates, said hangers having upper surfaces which slope downwardly and inwardly, lock bars having sloping upper portions supported on the sloping hanger surfaces and lower portions extending between the grate plates and the hangers, said hangers being provided with a longitudinal groove, and ribs on said lock bars extending freely into said grooves so as to permit a certain degree of relative movement between each lock bar and its associated hanger while preventing upward removal of saidlock bar.

9. A furnace grate comprising a pair of hangers, trunnion bars pivotally mounted in said hangers, grate plates secured to said trunnion bars, and a lock bar on one hanger extending between the grate plates and one of said hangers, said lock bar and hanger having inclined surfaces in contact whereby the lock bar is maintained in contact with said grate plates by gravity, said lock bar and hanger having rib and groove formations permitting limited vertical and lateral movements of the bar with respect to the hanger, said plates preventing lateral movement of the lock bar to permit its removal.

ROY W. FOSTER. 

